Conventional fluorometers used to perform analyte readings, are typically designed as versatile instruments that can use several types of excitation and emission filters and may be equipped with adjustable sensitivities, so that they may be configured for many different types of assays. The Turner BioSystems TBS-380, and the BioRad VersaFluor fluorometer are examples of the typical laboratory fluorometer. A significant drawback to this design is that the user must choose the filters and/or light sources to use, requiring the user to understand how fluorescence works, look up the excitation and emission values of their assay, understand how to choose the appropriate filter sets and possibly purchase and install new filter sets. In addition, the user must often determine the appropriate gain setting (sensitivity) of the instrument by an iterative process before beginning the assay. The extensive tables that are offered with these instruments illustrate the potential difficulties for the user in setting up the instrument to perform their assay of interest. In particular, if the user intends to use only one type of assay, this selection process presents a formidable barrier to using the instrument.
In addition, conventional fluorometers typically measure light emitted from the sample and display the readout in relative fluorescence values. Because the display is in relative fluorescence values, the user must, in general, use standards to generate a standard curve, plot the relative fluorescence values of the standards, fit a line to the curve, compare the relative fluorescence value of the samples to the standard curve, and ultimately back-calculate to determine the concentration of the sample. These operations can present difficulties to the untrained user and, even for the experienced user, these operations are tedious and time-consuming. Generally, a fluorometer can be configured to download data to a computer to make this operation easier. Unfortunately, this labor-saving feature requires installation of software onto a compatible computer, which may require purchasing a compatible computer, finding an appropriate communications port to transfer the data from the instrument to the computer, finding a suitable place in the laboratory where the instrument can permanently be connected to the computer and then hoping that the installed software will operate properly with the instrument. These actions can provide formidable barriers to the would-be user.
There is at least one fluorometer, the Turner BioSystems Modulus instrument, which has some software built in for performing calculations automatically from standards provided by the user, making the performance of those select assays easier for the user. The Turner fluorometer, however, requires five standards to calculate the standard curve, requiring a significant investment of time for the user, which may be particularly tedious if the user is measuring only a small number of samples. Finally, this instrument is again designed for maximal flexibility, offering separate modules for each assay, which must be snapped into the instrument and are small enough to be easily lost in a typical laboratory environment.
Typical fluorometers also use specialized cuvettes to hold the sample. In general, the cuvettes are unique to a specific instrument, require adapters for small sample sizes, are not generally available from standard laboratory supply companies and may be expensive.
What is desired in the art is a small device for the measurement of a defined set of assays. The device should be designed for seamless integration with the specific set of assays, such that the user-interface would allow the user to choose from a defined set of assays and immediately begin to perform the assay. Upon choosing the assay of interest, the device would automatically choose the correct light sources, filter sets and sensitivity settings for the assay chosen. In addition, the device would be designed with sophisticated algorithms for data analysis appropriate for the specific assays, such that the customer need only measure a small number of standards (2 or 3). The device would also be designed to calculate a standard curve from these standards, and upon measurement of the samples, the device would automatically perform the required analysis and simply display the concentration of the sample for the user. By building automatic configurations of light sources, filter sets and gain settings and by incorporating data analysis algorithms into the device, the user would no longer encounter a learning curve just to use the device. In addition, the user would not need to choose, purchase and install filters, or determine the gain setting or sensitivity of the instrument. Finally, the user would be spared the tedium of using a large number of standards for the curve, plotting the curve, fitting a line to the curve, comparing the value of the sample to the curve, and back-calculating the concentration of the sample from the standard curve equation. The device would have a small footprint and would not require connection to a computer, such that the instrument system would not require a large dedicated amount of benchspace. In addition, because the device would not require connection to a computer for data analysis, the difficulties of finding a compatible computer for the software, installing the software on the computer and connecting the device to the computer are eliminated. Finally, the device would use a readily-available, inexpensive, disposable, laboratory test-tube to minimize the stress and expense of finding appropriate replacement cuvettes for the instrument.